Intravascular membrane oxygenators represent a promising therapy for Acute Respiratory Distress Syndrome (ARDS), a medical condition that has a mortality rate of 50% due to hypoxemic respiratory failure. Intra- vascular oxygenators avoid the barotrauma and volutrauma associated with mechanical ventilation and have the potential to be effective, easy to use, and economical. However, practical application of oxygenators has been hampered by limitations of current membranes, which wet after several hours of blood contract. When this occurs, gas exchange is reduced to insufficient levels and the device requires replacement. The goal of this program is to develop improved nonwetting, biocompatible hollow-fiber membranes that have high gas permeabilities for use in intravascular oxygenators. In Phase I, we demonstrated that a composite membrane (which consists of a thin, nonporous coating applied to a microporous hollow-fiber support) did not wet and maintains sufficient gas permeability to achieve target gas-exchange levels. We worked with the University of Pittsburgh, developers of the Intravenous Membrane Oxygenator (IMO). Phase II work is aimed at optimization of the membranes, particularly their long-term performance in contact with blood (e.g., bio- compatibility and in vivo testing of the IMO device), readying the membranes and device for commercialization with our potential Phase III sponsors. PROPOSED COMMERCIAL APPLICATION: Development of the improved hollow-fiber membranes should make possible the practical application of intravascular blood oxygenators, extending the useful lifetime of the devices from about 6 hours to up to 3 weeks. The membranes also promise to be useful for other commercial products, including extracorporeal oxygenators and processes based on membrane contractors.